Method and system for automatically rerouting logical circuit data in a data network

ABSTRACT

A method and system are provided for automatically rerouting logical circuit data in a data network. A failure is identified in a logical circuit in a data network. The logical circuit may include a communication path for communicating data. Once the failure in the logical circuit is determined, a logical failover circuit is then identified. The logical failover circuit includes an alternate communication path for communicating the data for the failed logical circuit. After the logical failover circuit has been identified, the data from the failed logical circuit is rerouted to the logical failover circuit without manual intervention. After the data has been rerouted the logical failover circuit, a determination is made as to whether the failure in the logical circuit has been corrected. If it is determined that the failure in the logical circuit has been corrected, then the data from the logical failover circuit is rerouted back to the logical circuit in the data network without manual intervention.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to U.S. patent application Ser. No.10/348,077, entitled “Method and System for Obtaining LogicalPerformance Data for a Circuit in a Data Network,” filed on Jan. 21,2003, and U.S. patent application Ser. No. 10/348,592, entitled “Methodand System for Provisioning and Maintaining a Circuit in a DataNetwork,” filed on Jan. 21, 2003. This application is also related toand filed concurrently with U.S. patent application Ser. No. 10/745,117,entitled “Method And System For Providing A Failover Circuit ForRerouting Logical Circuit Data In A Data Network,” filed on Dec. 23,2003, U.S. patent application Ser. No. 10/744,281, entitled “Method AndSystem For Utilizing A Logical Failover Circuit For Rerouting DataBetween Data Networks,” filed on Dec. 23, 2003, U.S. patent applicationSer. No. 10/745,047, entitled “Method And System For AutomaticallyRenaming Logical Circuit Identifiers For Rerouted Logical Circuits In AData Network,” filed on Dec. 23, 2003, U.S. patent application Ser. No.10/745,170, entitled “Method And System For Automatically Identifying ALogical Circuit Failure In A Data Network,” filed on Dec. 23, 2003, U.S.patent application Ser. No. 10/745,168, entitled “Method And System ForAutomatically Rerouting Logical Circuit Data In A Virtual PrivateNetwork,” filed on Dec. 23, 2003, U.S. patent application Ser. No.10/745,116, entitled “Method And System For Automatically Rerouting DataFrom An Overbalanced Logical Circuit In A Data Network,” filed on Dec.23, 2003, U.S. patent application Ser. No. 10/744,283, entitled “MethodAnd System For Real Time Simultaneous Monitoring Of Logical Circuits InA Data Network,” filed on Dec. 23, 2003, U.S. patent application Ser.No. 10/744,555, entitled “Method And System For Prioritized Rerouting OfLogical Circuit Data In A Data Network,” filed on Dec. 23, 2003. All ofthe above-referenced applications are assigned to the same assignee asthe present application and are expressly incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to the routing of data using logicalcircuits in a data network. More particularly, the present invention isrelated to automatically rerouting data from failed logical circuits ina data network.

BACKGROUND OF THE INVENTION

Data networks contain various network devices, such as switches, forsending and receiving data between two locations. For example, framerelay and Asynchronous Transfer Mode (“ATM”) networks containinterconnected network devices that allow data packets or cells to bechanneled over a circuit through the network from a host device to aremote device. For a given network circuit, the data from a host deviceis delivered to the network through a physical circuit such as a T1 linethat links to a switch of the network. The remote device thatcommunicates with the host through the network also has a physicalcircuit to a switch of the network. A network circuit also includes alogical circuit which includes a variable communication path for databetween the switches associated with the host and the remote device.

In large-scale networks, the host and remote end devices of a networkcircuit may be connected across different local access and transportareas (“LATAs”) which may be in turn be connected to one or moreInter-Exchange Carriers (“IEC”) for transporting data between the LATAs.These connections are made through physical trunk circuits utilizingfixed logical connections known as Network-to-Network Interfaces(“NNIs”).

Periodically, failures may occur to the trunk circuits or the NNIs ofnetwork circuits in large-scale networks causing lost data. Currently,such network circuit failures are handled by dispatching technicians oneach end of the network circuit (i.e., in each LATA) in response to areported failure. The technicians manually access a logical elementmodule to troubleshoot the logical circuit portion of the networkcircuit. The logical element module communicates with the switches inthe data network and provides the technician with the status of thelogical connections which make up the logical circuit. Once thetechnician determines the status of a logical connection at one end of alogical circuit (e.g., the host end), the technician then must access anetwork database to determine the location of the other end of thelogical circuit so that its status may also be ascertained. If thetechnician determines the logical circuit is operating properly, thetechnician then accesses a physical element module to troubleshoot thephysical circuit portion of the network circuit to determine the causeof the failure and then repair it.

Current methods of determining network circuit failures, however, sufferfrom several drawbacks. One drawback is that troubleshooting logical andphysical circuits is time consuming and results in dropped data packetsor cells until the failure is isolated and repaired. Furthermoretroubleshooting the physical circuit often requires taking the networkcircuit out of service to perform testing, thus increasing the downtimeand loss of data in the logical circuit. Moreover, if the failure cannotbe isolated by the technicians in a LATA or the failure is located atthe interface to the IEC, cooperative testing with the IEC must also becoordinated to isolate the failure leading to a further increase indowntime and loss of data in the network circuit.

It is with respect to these considerations and others that the presentinvention has been made.

SUMMARY OF THE INVENTION

In accordance with the present invention, the above and other problemsare solved by methods for automatically utilizing logical failovercircuits for rerouting data from failed logical circuits in a datanetwork. When a failure in a logical circuit is detected, the data inthe circuit may be rerouted to a “logical failover network,” therebyminimizing lost data until the trouble in the logical circuit isresolved.

According to one method, a failure is identified in a logical circuit ina data network. The logical circuit may include a communication path forcommunicating data. Once the failure in the logical circuit isdetermined, a logical failover circuit is then identified. The logicalfailover circuit includes an alternate communication path forcommunicating the data for the failed logical circuit. After the logicalfailover circuit has been identified, the data from the failed logicalcircuit is rerouted to the logical failover circuit without manualintervention. After the data has been rerouted the logical failovercircuit, a determination is made as to whether the failure in thelogical circuit has been corrected. If it is determined that the failurein the logical circuit has been corrected, then the data from thelogical failover circuit is rerouted back to the logical circuit in thedata network without manual intervention.

In identifying a failure in the logical circuit, the method may includedetermining a failure in a logical connection in the logical circuit.The logical failover circuit may include a currently unused logicalconnection in the data network. In identifying the logical failovercircuit, the method may include identifying the currently unused logicalconnection. The logical failover circuit may include a dedicatedfailover logical connection in a failover data network. The logicalcircuit and the logical failover circuit may be identified by logicalcircuit identifiers. The logical circuit identifiers may be data linkconnection identifiers (“DLCIs”) or virtual path/virtual circuitidentifiers (“VPI/VCIs”). The logical connections comprising the logicalcircuit and the logical failover circuit may be network-to-networkinterfaces (“NNIs”). The method may further include renaming a logicalcircuit identifier of the failed logical circuit to the logical circuitidentifier of the logical failover circuit in the data network. Themethod may further include saving reroute data associated with thelogical circuit upon rerouting the logical circuit data. The logicalfailover circuit may be either is a switched permanent virtual circuit(“PVC”) or a switched virtual circuit (“SVC”). The data network and thefailover network may be either frame relay or asynchronous transfer mode(“ATM”) networks.

In accordance with other aspects, the present invention relates to asystem for automatically rerouting logical circuit data in a datanetwork. The system includes a network device for communicating statusinformation for a logical circuit in the data network, a logical elementmodule, in communication with the network device, for receiving thestatus information for the logical circuit in the data network, and anetwork management module in communication with the logical elementmodule. The network management module is operative to receive the statusinformation for the logical circuit, determine a failure of the logicalcircuit based on the status information, identify a logical failovercircuit and reroute the data from the logical circuit to the logicalfailover circuit without manual intervention. After rerouting the datato the logical failover circuit the network management module is furtheroperative to communicate with the logical element module to determinewhether the failure in the logical circuit has been corrected and if thefailure in the logical circuit has been corrected, then reroute the datafrom the logical failover circuit to the logical circuit in the datanetwork without manual intervention.

The network management module may determine a failure in a logicalconnection in the logical circuit to determine the logical circuitfailure. The logical circuit may be identified by a first logicalcircuit identifier in the data network while the logical failovercircuit may be identified by a second logical identifier in the datanetwork. The network management module may be further operative torename the first logical circuit identifier of the failed logicalcircuit to the second logical circuit identifier of the logical failovercircuit prior to rerouting the data from the logical circuit to thelogical failover circuit.

These and various other features as well as advantages, whichcharacterize the present invention, will be apparent from a reading ofthe following detailed description and a review of the associateddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a data network according to an embodiment of theinvention.

FIG. 2 illustrates a local access and transport area (“LATA”) in thedata network of FIG. 1, according to an embodiment of the invention.

FIG. 3 illustrates a network management system which may be utilized toautomatically reroute logical circuit data from a failed logical circuitin a data network, according to an embodiment of the invention.

FIG. 4 illustrates a failover data network for rerouting logical circuitdata in a data network, according to an embodiment of the invention.

FIG. 5 illustrates a flowchart describing logical operations forautomatically rerouting logical circuit data from a failed logicalcircuit in the data network, according to an embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention provide for a method and system forutilizing a logical failover circuit for automatically rerouting datafrom a logical circuit in a data network. When a failure in a logicalcircuit is detected, the data in the circuit may be rerouted to a“failover network,” thereby minimizing lost data until the failure inthe logical circuit is resolved. In the following detailed description,references are made to the accompanying drawings that form a parthereof, and in which are shown by way of illustration specificembodiments or examples. Referring now to the drawings, in which likenumerals represent like elements through the several figures, aspects ofthe present invention and the exemplary operating environment will bedescribed.

Embodiments of the present invention may be generally employed in a datanetwork 2 as shown in FIG. 1. The data network 2 includes local accessand transport areas (“LATAs”) 5 and 15 which are connected by anInter-Exchange Carrier (“IEC”) 10. It should be understood that theLATAs 5 and 15 may be data networks operated by a commonly owned LocalExchange Carrier (“LEC”). It should be further understood that the IEC10 may include one or more data networks which may be operated by acommonly owned IEC. It will be appreciated by those skilled in the artthat the data network 2 may be a frame relay network, asynchronoustransfer mode (“ATM”) network, or any other network capable ofcommunicating data conforming to Layers 2-4 of the Open SystemsInterconnection (“OSI”) model developed by the International StandardsOrganization, incorporated herein by reference. It will be appreciatedthat these networks may include, but are not limited to, communicationsprotocols conforming to the Multiprotocol Label Switching Standard(“MPLS”) networks and the Transmission Control Protocol/InternetProtocol (“TCP/IP”), which are known to those skilled in the art.

The data network 2 includes a network circuit which channels databetween a host device 112 and a remote device 114 through the LATA 5,the IEC 10, and the LATA 15. It will be appreciated by those skilled inthe art that the host and remote devices 112 and 114 may be local areanetwork (“LAN”) routers, LAN bridges, hosts, front end processors, FrameRelay Access Devices (“FRADs”), or any other device with a frame relay,ATM, or network interface. It will be further appreciated that in thedata network 2, the LATAs 5 and 15 and the IEC 10 may include networkelements (not shown) which support interworking to enable communicationsbetween host and remote devices supporting dissimilar protocols. Networkelements in a data network supporting interworking may translate framerelay data packets or frames sent from a host FRAD to ATM data packetsor cells so that a host device may communicate with a remote devicehaving an ATM interface. The LATAs 5 and 15 and the IEC 10 may furtherinclude one or more interconnected network elements, such as switches(not shown), for transmitting data. An illustrative LATA data networkwill be discussed in greater detail in the description of FIG. 2 below.

The network circuit between the host device 112 and the remote device114 in the data network 2 includes a physical circuit and a logicalcircuit. As used in the foregoing description and the appended claims, aphysical circuit is defined as the physical path that connects the endpoint of a network circuit to a network device. For example, thephysical circuit of the network circuit between the host device 112 andthe remote device 114 includes the physical connection 121 between thehost device 112 and the LATA 5, the physical connection 106 between theLATA 5 and the IEC 10, the physical connection 108 between the IEC 10and the LATA 15, and the physical connection 123 between the LATA 15 andthe remote device 114. Routers and switches within the LATAs 5 and 15and the IEC 10 carry the physical signal between the host and remote enddevices 112 and 114 through the physical circuit.

It should be understood that the host and remote devices may beconnected to the physical circuit described above using user-to-networkinterfaces (“UNIs”). As is known to those skilled in the art, an UNI isthe physical demarcation point between a user device (e.g, a hostdevice) and a public data network. It will further be understood bythose skilled in the art that the physical connections 106 and 108 mayinclude trunk circuits for carrying the data between the LATAs 5 and 15and the IEC 10. It will be further understood by those skilled in theart that the connections 121 and 123 may be any of various physicalcommunications media for communicating data such as a 56 Kbps line or aT1 line carried over a four-wire shielded cable or over a fiber opticcable.

As used in the foregoing description and the appended claims, a logicalcircuit is defined as a portion of the network circuit wherein data issent over variable communication data paths or logical connectionsestablished between the first and last network devices within a LATA orIEC network and over fixed communication data paths or logicalconnections between LATAs (or between IECs). Thus, no matter what paththe data takes within each LATA or IEC, the beginning and end of eachlogical connection between networks will not change. For example, thelogical circuit of the network circuit in the data network may 2 includea variable communication path within the LATA 5 and a fixedcommunication path (i.e., the logical connection 102) between the LATA 5and the IEC 10. It will be understood by those skilled in the art thatthe logical connections 102 and 104 in the data network 2 may includenetwork-to-network interfaces (“NNIs”) between the last sending switchin a LATA and the first receiving switch in an IEC.

As is known to those skilled in the art, each logical circuit in a datanetwork may be identified by a unique logical identifier. In frame relaynetworks, the logical identifier is called a Data Link ConnectionIdentifier (“DLCI”) while in ATM networks the logical identifier iscalled a Virtual Path Identifier/Virtual Circuit Identifier (“VPI/VCI”).In frame relay networks, the DLCI is a 10-bit address field contained inthe header of each data frame and contains identifying information forthe logical circuit as well as information relating to the destinationof the data in the frame and service parameters for handling networkcongestion. For example, in the data network 2 implemented as a framerelay network, the designation DLCI 100 may be used to identify thelogical circuit between the host device 112 and the remote device 114.It will be appreciated that in data networks in which logical circuitdata is communicated through more than one carrier (e.g., an LEC and anIEC) the DLCI designation for the logical circuit may change in aspecific carrier's network. For example, in the data network 2, thedesignation DLCI 100 may identify the logical circuit in the LATA 5 andLATA 15 but the designation DLCI 800 may identify the logical circuit inthe IEC 10.

Illustrative service parameters which may be included in the DLCIinclude a Committed Information Rate (“CIR”) parameter and a CommittedBurst Size (“Bc”) parameter. As is known to those skilled in the art,the CIR represents the average capacity of the logical circuit and theBc represents the maximum amount of data that may be transmitted. Itwill be appreciated that the logical circuit may be provisioned suchthat when the CIR or the Bc is exceeded, the receiving switch in thedata network will discard the frame. It should be understood that thelogical circuit parameters are not limited to CIR and Bc and that otherparameters known to those skilled in the art may also be provisioned,including, but not limited to, Burst Excess Size (“Be”) and CommittedRate Measurement Interval (“Tc”). In ATM networks, the VPI/VCI is anaddress field contained in the header of each ATM data cell and containsidentifying information for the logical circuit as well as informationspecifying a data cell's destination and specific bits which mayindicate, for example, the existence of congestion in the network and athreshold for discarding cells.

It should be understood that the logical circuit in the data network 2may be a permanent virtual circuit (“PVC”) available to the network atall times or a temporary or a switched virtual circuit (“SVC”) availableto the network only as long as data is being transmitted. It should beunderstood that the data network 2 may further include additionalswitches or other interconnected network elements (not shown) creatingmultiple paths within each LATA and IEC for defining each PVC or SVC inthe data network. It will be appreciated that the data communicated overthe logical connections 102 and 104 may be physically carried by thephysical connections 106 and 108.

The data network 2 may also include a failover network 17 for reroutinglogical circuit data, according to an embodiment of the invention. Thefailover network 17 may include a network failover circuit includingphysical connections 134 and 144 and logical connections 122 and 132 forrerouting logical circuit data in the event of a failure in the networkcircuit between the host device 112 and the remote device 114. Thefailover network 17 will be described in greater detail in thedescription of FIG. 4 below. The data network 2 may also include anetwork management system 175 in communication with the LATA 5, the LATA15, and the failover network 17. The network management system 175 maybe utilized to obtain status information for the logical and physicalcircuit between the host device 112 and the remote device 114. Thenetwork management system 175 may also be utilized for to reroutinglogical data in the data network 2 between the host device 112 and theremote device 114. The network management system 175 will be discussedin greater detail in the description of FIG. 3 below.

FIG. 2 illustrates the LATA 5 in the data network 2 described in FIG. 1above, according to an embodiment of the present invention. As shown inFIG. 2, the LATA 5 includes interconnected network devices such asswitches 186, 187, and 188. It will be appreciated that the data network2 may also contain other interconnected network devices and elements(not shown) such as digital access and cross connect switches (“DACS”),channel service units (“CSUs”), and data service units (“DSUs”). Asdiscussed above in the description of FIG. 1, the connection data pathsof a logical circuit within a data network may vary between the firstand last network devices in a data network. For example, as shown inFIG. 2, the logical circuit in the LATA 5 may include the communicationpath 185 between the switches 186 and 188 or the communication path 184between the switches 186, 187, and 188. As discussed above, it should beunderstood that the actual path taken by data through the LATA 5 is notfixed and may vary from time to time, such as when automatic reroutingtakes place.

It will be appreciated that the switches 186, 187, and 188 may include asignaling mechanism for monitoring and signaling the status of thelogical circuit in the data network 2. Each time a change in the statusof the logical circuit is detected (e.g., a receiving switch beginsdropping frames), the switch generates an alarm or “trap” which may thenbe communicated to a management station, such as a logical elementmodule (described in detail in the description of FIG. 3 below), in thenetwork management system 175. In one embodiment, the signalingmechanism may be in accord with a Local Management Interface (“LMI”)specification, which provides for the sending and receiving of “statusinquiries” between a data network and a host or remote device. The LMIspecification includes obtaining status information through the use ofspecial management frames (in frame relay networks) or cells (in ATMnetworks). In frame relay networks, for example, the special managementframes monitor the status of logical connections and provide informationregarding the health of the network. In the data network 2, the host andremote devices 112 and 114 receive status information from theindividual LATAs they are connected to in response to a status requestsent in a special management frame or cell. The LMI status informationmay include, for example, whether or not the logical circuit iscongested or whether or not the logical circuit has failed. It should beunderstood that the parameters and the signaling mechanism discussedabove are optional and that other parameters and mechanisms may also beutilized to obtain connection status information for a logical circuit.

FIG. 3 illustrates the network management system 175 which may beutilized to automatically reroute logical circuit data from a failedlogical circuit in the data network of FIG. 1, according to anembodiment of the invention. The network management system 175 includesa service order system 160, a network database 170, a logical elementmodule 153, a physical element module 155, a network management module176, and a test module 180. The service order system 160 is utilized inthe data network 2 for receiving service orders for provisioning networkcircuits. The service order includes information defining thetransmission characteristics (i.e., the logical circuit) of the networkcircuit. The service order also contains the access speed, CIR, burstrates, and excess burst rates. The service order system 160 communicatesthe service order information to a network database 170 over managementtrunk 172. The network database 170 assigns and stores the parametersfor the physical circuit for the network circuit such as a port numberon the switch 186 for transmitting data over the physical connection 121to and from the host device 112.

The network database 170 may also be in communication with an operationssupport system (not shown) for assigning physical equipment to thenetwork circuit and for maintaining an inventory of the physicalassignments for the network circuit. An illustrative operations supportsystem is “TIRKS”® (Trunks Integrated Records Keeping System) marketedby TELECORDIA™ TECHNOLOGIES, Inc. of Morristown, N.J. The networkdatabase 170 may also be in communication with a Work ForceAdministration and Control system (“WFA/C”) (not shown) used to assignresources (i.e., technicians) to work on installing the physicalcircuit.

The network management system 175 also includes the logical elementmodule 153 which is in communication with the switches in the datanetwork 2 through management trunks 183. The logical element module 153runs a network management application program to monitor the operationof logical circuits which includes receiving trap data generated by theswitches with indicate the status of logical connections. The trap datamay be stored in the logical element module 153 for later analysis andreview. The logical element module 153 is also in communication with thenetwork database 170 via management trunks 172 for accessing informationregarding logical circuits such as the logical identifier data. Thelogical identifier data may include, for example, the DLCI or VPI/VCIheader information for each data frame or cell in the logical circuitincluding the circuit's destination and service parameters. The logicalelement module 153 may consist of terminals (not shown) that display amap-based graphical user interface (“GUI”) of the logical connections inthe data network. An illustrative logical element module is theNAVISCORE™ system marketed by LUCENT TECHNOLOGIES, Inc. of Murray Hill,N.J.

The network management system 175 further includes the physical elementmodule 155 in communication with the physical connections of the networkcircuit via management trunks (not shown). The physical element module155 runs a network management application program to monitor theoperation and retrieve data regarding the operation of the physicalcircuit. The physical element module 155 is also in communication withthe network database 170 via management trunks 172 for accessinginformation regarding physical circuits, such as line speed. Similar tothe logical element module 153, the physical logical element module 155may also consist of terminals (not shown) that display a map-based GUIof the physical connections in the LATA 5. An illustrative physicalelement module is the Integrated Testing and Analysis System (“INTAS”),marketed by TELECORDIA™ TECHNOLOGIES, Inc. of Morristown, N.J., whichprovides flow-through testing and analysis of telephony services.

The physical element module 155 troubleshoots the physical connectionsfor a physical circuit by communicating with test module 180, whichinterfaces with the physical connections via test access point 156. Thetest module 180 obtains the status of the physical circuit bytransmitting “clean” test signals to test access point 156 (shown inFIG. 2) which “loops back” the signals for detection by the test module180. It should be understood that there may multiple test access pointson each of the physical connections for the physical circuit.

The network management system 175 further includes the networkmanagement module 176 which is in communication with the service ordersystem 160, the network database 170, the logical element module 153,and the physical element module 155 through communications channels 172.It should be understood that in one embodiment, the network managementsystem 176 may also be in communication with the LATA 15, the IEC 10,and the failover network 17. The communications channels 172 may be on aLAN. The network management module 176 may consist of terminals (notshown), which may be part of a general-purpose computer system thatdisplays a map-based GUI of the logical connections in data networks.The network management module 175 may communicate with the logicalelement module 153 and the physical element module 155 using a CommonObject Request Broker Architecture (“CORBA”). As is known to thoseskilled in the art, CORBA is an open, vendor-independent architectureand infrastructure which allows different computer applications to worktogether over one or more networks using a basic set of commands andresponses. The network management module 176 may also serve as aninterface for implementing logical operations to provision and maintainnetwork circuits. The logical operations may be implemented as machineinstructions stored locally or as instructions retrieved from thelogical and physical element modules 153 and 155. An illustrative methoddetailing the provisioning and maintenance of network circuits in a datanetwork is presented in U.S. patent application Ser. No. 10/348,592,entitled “Method And System For Provisioning And Maintaining A CircuitIn A Data Network,” filed on Jan. 23, 2003, and assigned to the sameassignee as this application, which is expressly incorporated herein byreference. An illustrative network management module is the BroadbandNetwork Management System® (“BBNMS”) marketed by TELECORDIA™TECHNOLOGIES, Inc. of Morristown, N.J.

FIG. 4 illustrates a failover data network for rerouting logical circuitdata, according to one embodiment of the present invention. As shown inFIG. 4, the failover network 17 includes an IEC 20, a LATA 25, and anIEC 30. The failover network further includes a network failover circuitwhich includes a physical failover circuit and a logical failovercircuit. The physical failover circuit includes the physical connection134 between the LATA 5 (shown in FIG. 1) and the IEC 20, the physicalconnection 136 between the IEC 20 and the LATA 25, the physicalconnection 138 between the LATA 25 and the IEC 30, and the physicalconnection 144 between the IEC 30 and the LATA 15 (shown in FIG. 1).Similarly, the logical failover circuit may include the logicalconnection 122 between the LATA 5 (shown in FIG. 1) and the IEC 20, thelogical connection 124 between the IEC 20 and the LATA 25, the logicalconnection 126 between the LATA 25 and the IEC 30, and the logicalconnection 132 between the IEC 30 and the LATA 15 (shown in FIG. 1). Itshould be understood that in one embodiment, the network failovercircuit illustrated in the failover network 17 may include a dedicatedphysical circuit and a dedicated logical circuit provisioned by anetwork service provider serving the LATAs 5, 15, and 25 and the IECs 20and 30, for rerouting logical data from a failed logical circuit.

FIG. 5 illustrates a flowchart describing logical operations 500 forautomatically rerouting logical circuit data in a data network,according to an embodiment of the invention. It will be appreciated thatthe logical operations 500 may be initiated by a customer report of anetwork circuit failure is received in the data network 2. For example,a customer at the remote device 114 may determine that the remote device114 is not receiving any data (e.g., frames or cells) sent from the hostdevice 112 (e.g., by reviewing LMI status information in the hostdevice). After receiving the customer report, the network serviceprovider providing the network circuit may open a trouble ticket in theservice order system 160 to troubleshoot the logical circuit.

The logical operations 500 begin at operation 505 where the networkmanagement module 176 receives status information for a logical circuitin the data network 2. It will be appreciated that in one embodiment,the status information may be received by communicating with the logicalelement module 153 to request trap data generated by one or moreswitches in the data network which indicate the status of one or morelogical connections making up the logical circuit. It will beappreciated that in one embodiment of the present invention, thecommunication of the status information for the logical circuit may bemanually initiated by a technician from a terminal in the networkmanagement module 176. In another embodiment of the present invention,the network management module 176 may be configured to automaticallymonitor the logical circuits or the switches storing trap data toidentify a logical circuit failure in the data network 2. Anillustrative method detailing the automatic monitoring of logicalcircuits to identify a logical circuit failure in a data network ispresented in co-pending U.S. patent application Ser. No. 10/745,170,entitled “Method And System For Automatically Identifying A LogicalCircuit Failure In A Data Network,” filed on Dec. 23, 2003, and assignedto the same assignee as this application, which is expresslyincorporated herein by reference.

After receiving the status information for the logical circuit atoperation 505, the logical operations 500 continue at operation 510where the network management module 176 determines whether a logicalcircuit failure has occurred based on the received status information.It should be understood that a logical circuit failure occurs when oneor more logical connections in a logical circuit have failed. Asdiscussed above in the description of FIG. 2, trap data indicating alogical connection failure may include status information indicatingthat a switch in the data network is discarding frames or cells. Such anevent may occur, for example, when the maximum CIR or Bc (as specifiedin the DLCI of a frame in a frame relay network, for example) isexceeded. For example, in the data network 2 shown in FIG. 1, the “X”marking the logical connections 102 and 104 indicate that bothconnections are “down beyond” (i.e., not communicating data) the NNIsfor the logical circuit in the LATA data networks 5 and 15. In thisexample, such a condition may indicate that the logical circuit failurelies in the IEC data network 10.

If at operation 510, it is determined that a logical circuit failure hasnot occurred, the logical operations 500 then return to operation 505where the network management module 176 again receives statusinformation for the logical circuit. If, however, at operation 510 it isdetermined that a logical circuit failure has occurred, the logicaloperations continue to operation 515. At operation 515, the networkmanagement module 176 identifies a logical failover circuit forrerouting the data from the logical circuit in the data network. Forexample, if as shown in FIG. 1, it is determined that the logicalcircuit failure in the data network 2 has been isolated to the IEC datanetwork 10, a logical failover circuit in the failover network 17 may beselected to reroute the logical data such that it bypasses the IEC datanetwork 10. For example, the logical failover circuit may be selectedincluding the logical connections 122, 124, 126, and 132 (as shown inFIG. 4) to reroute the logical data from the host device 112, throughthe LATA 5, the IEC 20, the LATA 25, the IEC 30, the LATA 15, andfinally to the remote device 114.

It will be appreciated that in one embodiment, the logical failovercircuit selected may be a dedicated circuit which is only utilized forrerouting logical data from a failed logical circuit (i.e., the failovercircuit does not normally communicate data traffic). In anotherembodiment, the logical failover circuit may include a logicalconnection which is normally utilized for communicating data traffic ina data network. In this embodiment, the selection of the logicalfailover circuit may also include determining whether one or morelogical connections in the circuit are currently communicating datatraffic or are currently unused. If currently unused, the logicalconnections may be selected for rerouting logical data.

It should be understood that in one embodiment, the selection of thelogical failover circuit may be manually initiated. For example, atechnician at the logical element module 153 or the network managementmodule 176 may utilize a map-based graphical user interface (GUI)displaying the logical connections in the LATA data networks 5 and 15and their status. A dedicated logical failover circuit (or a currentlyunused logical circuit with available logical connections) may then beselected as a logical failover circuit for communicating logical datafrom a failed logical circuit. The logical operations 500 then continuefrom operation 515 to operation 520.

As discussed above, the logical circuits in a data network areidentified by a logical circuit identifier (ID). At operation 520, thenetwork management module 176 compares the identifier (e.g. the DLCI orVPI/VCI) of the failed logical circuit to the identifier of the selectedlogical failover circuit. If at operation 520, it is determined that theidentifiers of the failed logical circuit and the logical failovercircuit are the same, the logical operations 500 then continue fromoperation 520 to operation 530. If, however, at operation 520 it isdetermined that logical circuit identifiers of the failed logicalcircuit and the logical failover circuit are not the same, the logicaloperations 500 then continue from operation 520 to operation 525 wherethe network management module 176 renames the logical circuit ID of thefailed logical circuit to the ID of the logical failover circuit in thedatabase 170. The logical operations 500 then continue from operation525 to operation 530. It will be appreciated that in the failovernetwork 17, a dedicated failover logical circuit may be assigned to anexisting logical circuit in a data network and identified with the sameID as the existing logical circuit. However, a logical failover circuitwhich is already an existing logical circuit (i.e., normallycommunicates data traffic in a data network) is already assigned aunique logical circuit ID. Thus, in the presently described embodimentof the invention, the logical identifier of a failed logical circuit maybe renamed so that it is in accord with a current logical identifier ofa logical failover circuit. For example, in a frame relay data network,a logical circuit may be identified as DLCI 100 while a logical failovercircuit may be identified as DLCI 250. The logical circuit may berenamed from DLCI 100 to DLCI 250. It will further be appreciated thatthe network management module 175 may store the changes to logicalcircuit identifiers as reroute data in the database 170. This reroutedata may then be accessed to rename the logical identifier of the failedlogical circuit once the trouble in the failed logical circuit has beenrepaired.

At operation 530 the network management module 176 reroutes the datafrom the failed logical circuit to the logical failover circuit. It willbe appreciated that the reroute of the data may be accomplished from thelogical management module 153 or the network management module 176which, in communication with the switches in the data network 2 (and thefailover network 17), sends instructions to reroute the logical datafrom the NNIs or logical connections 102 and 104 to the failover NNIs orlogical connections 122, 124, 126, and 132 in the logical failovercircuit. The logical operations 500 then continue from operation 530 tooperation 535.

At operation 535, the network management module 176 determines thefailed logical circuit has been restored. This determination may bemade, for example, by continuous or periodic logical circuit monitoringof the link status of the failed logical circuit, which may be performedby the logical element module 153 in communication with the networkmanagement module 176, to establish that the logical connections 102 (atthe LATA 5) and 104 (at the LATA 15) are successfully communicatingdata. If at operation 535 it is determined that the failed logicalcircuit has not been restored, the logical operations 500 return tooperation 530 where the rerouting of the data is maintained on thelogical failover circuit. If however, at operation 535, it is determinedthat the failed logical circuit has been restored, then the logicaloperations 535 continue to operation 540 where the data on the networkfailover circuit is rerouted back to the restored logical circuit.Similar to the rerouting of the logical data onto the logical failovercircuit, the rerouting of the logical data back onto the restoredlogical circuit may be accomplished from the network management module176 which, in communication with the switches in the data network 2 (andthe failover network 17) sends instructions to reroute the data from thefailover NNIs or logical connections 122, 124, 126, and 132 to therestored NNIs or logical connections 102 and 104 in the restored logicalcircuit. The logical operations 500 then end.

It will be appreciated that in one embodiment the logical circuitfailover procedure may be initiated as part of a customer subscriptionservice offered by the network service provider. The subscriptionservice may include use of the logical failover circuit for apredetermined time period after the customer's data has been rerouted.For example, a customer subscribing to the failover service wouldautomatically have the logical circuit failover procedure initiated andthe customer's data would be rerouted for up to two hours over thelogical failover circuit after a determination that the customer'snetwork circuit has failed. If a customer is not a subscriber, thefailover service may still be initiated and the customer may be billedbased on the length of time the failover service was in service. Inanother embodiment, the customer may be offered the failover service bythe service provider in real-time (i.e., upon determining a networkcircuit failure).

It will be appreciated that the embodiments of the invention describedabove provide for a method and system for automatically rerouting datafrom a failed logical circuit in a data network. When a failure in alogical circuit is detected, the data in the circuit may be rerouted toa “failover network,” thereby minimizing lost data until the failure inthe logical circuit is resolved. The various embodiments described aboveare provided by way of illustration only and should not be construed tolimit the invention. Those skilled in the art will readily recognizevarious modifications and changes that may be made to the presentinvention without following the example embodiments and applicationsillustrated and described herein, and without departing from the truespirit and scope of the present invention, which is set forth in thefollowing claims.

1. A method of automatically rerouting logical circuit data in a datanetwork, the method comprising: determining, via a network managementsystem, a failure of a logical connection in a logical circuit in thedata network, the logical circuit identified by a logical circuitidentifier in the data network, the logical circuit comprising variablecommunication paths in at least one of a local access and transport areaor an inter-exchange carrier and a fixed communication path between thelocal access and transport area and the inter-exchange carrier, and thefailed logical connection being between the local access and transportarea and the inter-exchange carrier; identifying, via the networkmanagement system, a logical failover circuit comprising an alternatecommunication path to communicate the data, the logical failover circuitlocated in a failover network that is separate from the logical circuit,the failover network being reserved to provide failover circuits tocommunicate data rerouted from failed logical circuits, and the logicalfailover circuit identified by a second logical circuit identifier inthe data network; renaming the logical circuit identifier of the logicalcircuit to the second logical circuit identifier of the logical failovercircuit; and rerouting the data to the logical failover circuit withoutmanual intervention.
 2. The method of claim 1, further comprising: afterrerouting the data to the logical failover circuit, determining whetherthe failure in the logical circuit has been corrected; and if thefailure in the logical circuit has been corrected, then rerouting thedata from the logical failover circuit to the logical circuit in thedata network without manual intervention.
 3. The method of claim 1,further comprising saving reroute data upon rerouting the data to thelogical failover circuit.
 4. The method of claim 1, wherein the logicalconnection comprises a network-to-network interface.
 5. The method ofclaim 1, wherein the logical circuit identifier is one of a virtualpath/virtual circuit identifier (VPI/VCI) or a data link connectionidentifier (DLCI).
 6. The method of claim 1, wherein the logicalfailover circuit is a permanent virtual circuit.
 7. The method of claim1, wherein the logical failover circuit is a switched virtual circuit.8. The method of claim 1, wherein the data network is one of anasynchronous transfer mode (ATM) network or a frame relay network. 9.The method of claim 1, wherein the failure in the logical connectioncomprises the logical connection no longer communicating data.
 10. Themethod of claim 1, further comprising: after determining the failure inthe logical circuit and before rerouting the data to the logicalfailover circuit, offering a failover service in real time to a customerassociated with the logical circuit; and performing the rerouting of thedata to the logical failover circuit in response to receiving acceptanceof the failover service by the customer.
 11. The method of claim 1,wherein the network management system is in communication with the localaccess and transport area and separate from switches over which the datais communicated through the logical circuit and the logical failovercircuit.
 12. The method of claim 1, further comprising after determiningthe failure in the logical circuit, performing the rerouting of the datato the logical failover circuit based on a customer subscription to afailover service, the data to be rerouted for a time period defined inthe customer subscription.
 13. The method of claim 1, wherein the localaccess and transport area is operated by a first carrier different fromthe inter-exchange carrier, and wherein the logical failover circuit ofthe failover network reroutes the data around the inter-exchangecarrier.
 14. A system to automatically reroute logical circuit data in adata network, the system comprising: a network device to communicatestatus information for a logical circuit, the logical circuit identifiedby a first logical circuit identifier in the data network, and thelogical circuit comprising variable communication paths in at least oneof a local access and transport area or an inter-exchange carrier and afixed communication path between the local access and transport area andthe inter-exchange carrier; a logical element module, in communicationwith the network device, to receive the status information for thelogical circuit in the data network; and a network management module, incommunication with the logical element module, to: determine a failureof a logical connection in the logical circuit based on the statusinformation, the failed logical connection being between the localaccess and transport area and the inter-exchange carrier; identify alogical failover circuit comprising an alternate communication path tocommunicate the data, the logical failover circuit located in a failovernetwork that is separate from the logical circuit, the failover networkbeing reserved to provide failover circuits to communicate data reroutedfrom failed logical circuits, and the logical failover circuitidentified by a second logical circuit identifier in the data network;rename the first logical circuit identifier identifying the logicalcircuit to the second logical circuit identifier identifying the logicalfailover circuit prior to rerouting the data from the logical circuit tothe logical failover circuit; and reroute the data from the logicalcircuit to the logical failover circuit without manual intervention. 15.The system of claim 14, wherein the logical failover circuit comprisesat least one unused logical connection.
 16. The system of claim 15,wherein the at least one unused logical connection comprises anetwork-to-network interface.
 17. The system of claim 14, wherein thefirst logical circuit identifier is one of a virtual path/virtualcircuit identifier (VPI/VCI) or a data link connection identifier(DLCI).
 18. The system of claim 14, wherein the logical failover circuitis a permanent virtual circuit.
 19. The system of claim 14, wherein thelogical failover circuit is a switched virtual circuit.
 20. The systemof claim 14, wherein the data network is one of an asynchronous transfermode (ATM) network or a frame relay network.
 21. The system of claim 14,wherein the logical failover circuit of the failover network reroutesthe data around the inter-exchange carrier.
 22. The system of claim 14,wherein the failure in the logical connection comprises the logicalconnection no longer communicating data.
 23. The system of claim 14,wherein the network management module is further to: after determiningthe failure in the logical circuit and before rerouting the data to thelogical failover circuit, offer a failover service in real time to acustomer associated with the logical circuit; and perform the reroutingof the data to the logical failover circuit in response to receivingacceptance of the failover service by the customer.
 24. The system ofclaim 14, wherein the logical element module and the network managementmodule are in communication with the local access and transport area andseparate from switches over which the data is communicated through thelogical circuit and the logical failover circuit.
 25. The system ofclaim 14, wherein the local access and transport area is operated by afirst carrier different from the inter-exchange carrier.